1. Field of the Invention
This invention relates to a milling machine and to a method of cutting a keyway in a shaft while the shaft is in a machine on site.
2. Background Information
In machines with heavy shafts, for example, steel rolling mills and paper mills, the keyways of the rolls are subject to wear and need to be renewed regularly. One can repair them by cutting them somewhat wider and then use wider keys. The keys and the milling heads are available in standard widths. Alternatively, one can add a weld seam to a keyway and then cut the keyway to the original width.
U.S. Pat. No. 3,466,972 shows and describes a portable milling machine which can be used on a shaft without the shaft being dismounted from a machine. The milling machine has a guideway that is to be clamped on the shaft and a cutting unit with a milling head that can be moved along the guideway. The milling head cuts the entire width of the keyway in one sweep. The transverse forces will be great and can jeopardize the precision by causing lateral movement. Therefore, the machine must be comparatively heavy and the accessibility in narrow places will be reduced.
It is a possible object of the invention to provide for a comparatively small machine that is essentially low in weight and power and has a better accessibility than known art machines but still has the same precision or even better precision than prior art machines.
This may be achieved in principle by a machine that has a cutting unit that may be laterally displaceable. A milling head with a diameter smaller than the keyway may be used and the keyway may be cut in more than one sweep.
The above-discussed embodiments of the present invention will be described further hereinbelow with reference to the accompanying figures. When the word xe2x80x9cinventionxe2x80x9d is used in this specification, the word xe2x80x9cinventionxe2x80x9d includes xe2x80x9cinventionsxe2x80x9d, that is, the plural of xe2x80x9cinventionxe2x80x9d. By stating xe2x80x9cinventionxe2x80x9d, Applicant does-not in any way admit that the present application does not include more than one patentably and non-obviously distinct invention, and maintains that this application may include more than one patentably and non-obviously distinct invention. Applicant hereby asserts that the disclosure of this application may include more than one invention, and, in the event that there is more than one invention, that these inventions may be patentable and non-obvious one with respect to the other.